In French patent application No. 87.08050 filed on June 10, 1987 and published under No. 2,616,337 (corresponding to U.S. Pat. No. 4,935,887, issued June 19, 1990), a process is described whereby curves of the variations of the different components of the movement of a horse can be traced and reconstructed in a simulator.
According to this process, measuring means such as accelerometers and gyrometers are placed on a horse in real motion, or also an inertial control unit. With these instruments, the speeds of linear displacement along the three axes X, Y and Z as well as the rotational displacements about these axes are measured.
To perform this process, at first an inertial unit of the type used in airplanes, was attached on the saddle of a horse, and to this inertial unit a magnetic recording device was coupled. Such equipment soon proved to be unsatisfactory. In fact, such relatively heavy and bulky equipment excludes the presence of a rider so that the horse is left to itself and one is obliged to prod it to record the various gaits (walk, trot, gallop, jump). Therefore, such measurements give only indications relating to a circular course or represent only short straight lines. Besides, unavoidably, the center of gravity of such rather voluminous equipment is located too high above the horse's back; this falsifies the acceleration measurements and makes it necessary to introduce error correction calculations, which are only approximations. Lastly, because this equipment is heavy and fastened above the saddle, it is difficult to prevent the equipment from being subjected to parasitic motions due to swinging, and this, too, falsifies the measurements and is very complicated to correct.
It has been proposed, therefore, to use a metallic oversaddle, that is, a metal part shaped so that it exactly matches the form of a classic leather saddle; and on this oversaddle has been welded a metal platform carrying three gyrometers, and three accelerometers.
Thus, it has been possible to eliminate practically all parasitic movements of the measuring means; but, although the center of gravity of this equipment has been lowered, it is still some twelve centimeters above the horse's back. Of greatest importance, as before, the horse was still without a rider.